Control of wild oats



United States Patent O This invention is concerned with the control` of wild oats and is particularly directed to the application of 1,2,4,5tetrachlorobenzene for preventing vthe growth of Y the seeds and emerging seedlings of wild oats.

Wild oats is anfannual weed which has steadily spread across the prairie lands of North America during the last half century. Unlike most other annual weeds, wild oats 'has proved resistant to pre-emergence application of 2,4-dieh1orophenoxy-acetic acid and the other weed kiuing chemicals now available. The annual loss among North American farmers attributable to this grass-like weed approaches a quarter of a million dollars. The weed infests more than forty million acres'in Canada and lmore than twenty million acres of prairie land in the United States. Thus, the necessity for a method for the control of wild oats is well recognized by the agriculturalist. y

`The use of halobenzenes for the treatment of seed grains is disclosed in United States Patent 1,947,926. In such use the seed grains are dressed with compositions containing halobenzene's such as hexachlo'robenzene, tetrabromobenzene, and tetra-halogeno-benzene. The treatment is taught tocontrol the fungal type diseases of smut of wheat (Tilletia trtc) and Fusarium ntvale of rye. It is anoobject ofjthe present inventionl to provide a new and 'improved method for the suppressionand control of the growth'of wild oats. A further'object is to provide a method for preventing the growth of the seeds o and emerging seedlings of wild oats. Another object is the` provision of a method for the suppression ofthe growth ofthe Yseedsand emerging seedlings of wild oats in soil'or growth' media which vis plantedwith the seeds of broad leaf crop plants. An additional object is the provision of'nove'l compositionsto be Aemployed vfor the 'y l 2,945,752 Patented` July 19, 19,670

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the control of the growth of wild oats. Further, the isomers of 1,2,4,5tetrachlorobenzene such as 1,2,3,4tetra chlorobenzene and l,2,3,5tetrachlorobenzene have been lfound to be without substantial herbicide activity.

l The introduction of 1,2,4,5tetrachlorobenzene in soil gives rise to varying degrees of response in seeds, emerging seedlings and growing plants depending upon the nature of the plant and the concentration of the compound inthe growth medium. When the compound is dispersed in growth media, in high concentrations, autemporary suppression of the growth of many seeds and plants is obtained. The weathering action ofthe sun and rain, and possibly 'the decomposition of the toxic compound by bacteria and other soil `organism-seventually frees `the growth medium of the toxicant. Lower concentrations of the 1A5-tetrachlorobenzene compound prevent the growth of the seeds and emerging seedlings of wild oats while having little or lno eiect upon the growth of the seeds and emerging seedlings of many broad leaf crop plants. Thus, it is possible to accomplishra selective control of wild oats in the presence of broad leaf crop plants such as peas,- beans, cotton and corn. A. o

The* lower concentrations of the tetrachlorobenhme compound in growth media exert a retarding and stunting effect uponvthe growth of many narrow leaf crop species. The degree `of stunting is dependent upon the nature of the narrow leaf crop plant and the concentration of the tetrachlorobenzene compounds4 in the soil. Where the treated soil is to be planted to iax,l wheat or lbarley, the planting operation should not be carried out for a period of.l from 2 to 4 weeks followingthe treatment, the exact period depending upon the concentration of the benzene compound in the soil.` When following such practice, the wild oats may becontrolled without substantial in jury to the grain crops. o l

In a particularly advantageous method of operation, the treatment of the soil with the tetrachlorobenzene compound is carried out after harvest. At this time the wildfoat plants have matured and their seeds have been scattered on the soilsurface in the fields. ,Following such post-harvest treatment, the Afields may be planted in the `fall or spring `in accordance with conventional procedure. Such practice `gives excellent control of wild oats.`

The distribution of Ia growthrinhibiting amount of the -I,2.4,S-tetrachlorobenzeneA compound in soil or growth media is essential vand critical 'for the practice ofA the present invention. In non-selective applications to `growth media, good results.Vv are obtained when thebenzene compound is vsupplied n the amount of from about 8 to 300 parts or more by weight per million'parts by weight of the media. In applications to field soil, good solid material melting at 139-l40 C., somewhat soluv ble in many organic solvents and of very low solubility in water. IIt has been found to have a very high degree of .toxicity Vagainst the seeds and emerging seedlings of wild oats and a very low toxicity for the seeds of many crop plants. Thus, the compound may be employed for the selective control Aof the growth of the seeds and emerging seedlings of wild oats in growth media planted with the seeds of broad leaf crop plants such as peas, cotton, beans, and corn. Also, the compound is adapted to be readily and conveniently distributed' in soil or growth media for A results are obtainedwhen the tetrachlorobenzene Oompound is distributed at a rate of iive pounds per acre and through such a cross section of the soil'as to provide lfor the presence therein of an eiective concentration of the treating agent. In field applications, it is desirable that the benzene compound be distributed -to a depth of at least' 0.5 inch and fat ,a substantially uniform concentration of at least 1.7 pounds per acre inch of soil.

In selective applications for the control of the growth of the seeds and emerging seedlings of wild oats in areas planted or to be planted with the seeds of many broad leaf plant species, a `concentration of from about 8 to about SOparts by weightv of toxicant permiIl-ion parts by `weight of growth medium may be employed. In such applications, the exact 4concentration to be employed is dependent upon the resistance of the seeds and emerging 3 seedlings' of the broad leaf crop plants to the tetrachlorobenzene compound.

The method of the present invention may be carried out by -applying to land mixing with the growth media the unmodified tetrachlorobenzene compound. However, the present method also embraces the employment of liquid or dust compositions-containing the toxicant. In such usage, the tetrachlorobenzene compound may be modified with oneA or a plurality of addit'ame-nts or herb- 'icide adjuvants such as water, organic solvents petroleum distillates, or other liquid carriers,` surface active ldispersing agents, and finely divided solids. Depending upon the concentration of toxicant, such modified com lpositions are adaptedto be distributed in soil, or em- 'pployed as concentrates and subsequently diluted with additionalinert'carrier to produce the ultimate treating compositions. The required amount of the tetrachloro, benzene compound in the growth media conveniently :may be supplied, per acre-treated, in from 40 to 27,7000 gallons or moreof liquid carrier or in from about 50 to 2,000 pounds or more of the inert solid carrier. The exact concentration of the tetrachlorobenzene icompound to be employed in compositions'for the treat f'ment of growth media is not critical and may Yvary considerably Yprovided the required dose of effective agent is supplied in the soil. kThe concentration of toxicant in liquid compositions employed lto supply the desired dosage generally is from about 0.001 to 50 percent by weight, although as highv a concentration as 90 percent by' weight may be employed. In solid compositions, theconcen'- tration of toxicant may be from about l to 50 percent by weight. In compositions to be employed as concentrates, the benzene 'compound maybe present in ay concentra- Vtion of from about to 95 percent by weight. o Liquid compositions containing the l,2,4`,5tetrachloro `|benzene compound may be prepared by dissolving the -toxic'ant inl an organic liquid such as xylene or petroleum distillates, or by dispersing the toxicant in water with lithe aid of alsuitable surface-active dispersing agent such Fasi an ionic or non-ionic emulsifying agent. 'I'he aqueous compositions may contain one or more water-immiscible 'solvents for the benzene compound. In. such compositions, the carrier` comprises an aqueous emulsion, i.e. a mixture of water-immiscible solvent, emulsifyingV agent and water.V Y .Y f,

The choice of dispersing and emulsifying agent and 'amount thereof employed isdictated by the nature of the composition type and bythe ability ofthe agent to facilitate the dispersion of the compound in the aqueous car- Yrier to Yproduce the desired composition.t Dispersngand emulsifying agents` which may be employed in the com- :positions include the condensation products of alkylene oxides with phenols and organic acids, alkyl aryl 'sulfohates, polyoxyethylene derivatives of sorbitan esters, com- 'plex ether alcohols, mahogany soaps and the like.

vIn the preparation of solid compositions, the tetra- When operating in accordance with the present invention, growth inhibiting amounts of the tetrachlorobenzene compound or a composition containing the toxicant are dispersed in any convenient fashion in soil or other growth media, i.e. by simple mixing with the growth media, by applying to the surface of soil and thereafter dragging or discing into the soil to the desired depth, or by employing a liquid carrier to' accomplish the penetration and impregnation. The application of the spray and dust compositions -may be carried out by conventional methods, e.g. with power clusters, boom or hand sprayers and spray dusters.

In a further method, the distribution may be accomplished by introducing the toxicant in the water employed to irrigate the soil. In such procedure, the amount of water may be varied in accordance with the porosity and water holding capacity of the soil vin order to obtain the desired depth of distribution of the toxicant.

The following examples ,illustrate the invention but are not to be construed as limiting.

i Fifty parts by weight .ofV 1,2,4,5-tetrachlorobenzene, :45 partsof fullers earth, 2parts ofan alkyl aryl sul- "foriate (Nacconol NR) and 3 parts of a polymerized sodium salt of substituted benzoid alkyl sulfonic acid (Daxad No. 27) were mechanically mixed and ground i 'together to prepare a concentrate composition in the formV ofa wettable powder. ,This composition was dispersed in water to produce two aqueous spray composi- 1ionscontaining 20 and 40 pounds of the tetrachlorobenzene compound per 100 gallons of ultimate mixture.

' what control of the growth of wild oats had been obclgllorobenzene compound is dispersed in and on a' finely -divided inert solid such as talc, chalk, gypsum, vermiculite, ground walnut shells, commercial fertilizer and the like. In such operations, the carrier is mixed with the 'toxicant in finely divided. forms, mechanically ground with the toxicant, or wet with a volatile organic solvent solution thereof. Similarly, dust compositions containing lfthe toxicant may be prepared from various of the solid surface-active dispersing agents, such' as bentonite, fullers `earth, attapulgite and other clays. Depending-'upon the proportions of `ingredients these compositions may be employed as vconcentrates and subsequently diluted with additional solid surface-active dispersing agent or with talc, chalk or gypsum 'and the like to obtain the desired amount of active ingredient in a composition adapted to be applied for the control of vegetative growth. Also, the dust compositions may be dispersed in water with or 'without the aid of a dispersing agent to forni spray mixtures.

persed in water to produce aqueous compositions contained. The' examination showed a 99.5 and 95 percent control of wild oats at dosages of 20 and 10 pounds of 1,2,4,5tetrachlorobenzene per acre, respectively. In the untreated portion .of the field there was found a heavy lsztlzitlnd of Wild oat plants which were from 8 to 12 inches Example II Y Twenty-five parts by weight of l,2,4,5tetrachlorobenzene, 71 parts of fullers earth, 2 parts of Nacconol NR and 2 parts of Daxad No'. 27 were mechanically mixed and ground together to prepare a concentrate composition in the form of a wett'able powder. In a similar manner wettable powder-concentrates were compounded vcontaining l,2,3,5-tetrachlorobenzene, l,2,4,5tetrabromobenzene, and 1,2,3,4tetrachlorobenzene.

Portions of these concentrate compositions` were distaining various amounts of each of Vthe'tetrahalobenzene compounds per gallons. of ultimate mixture.

Ymentof sandy loam soil of good nutrient content for 'the control of the growth of wild oats. In such operations, the compositions were applied to the soil areas as a soil drench and at a rate of about 0.43. acre-inch of aqueous composition per acre to supply-various amounts of tetrahalobenzene compounds .peracre and. various concentrations in the treated soil. Immediately vprior to the applications, the soil areas had been prepared and nseeded to wild oats. Other areas similarly prepared and seeded to wild oats were` left untreated to serve as cheeks. After three weeks, the treated areas' were examined to ascertain what control of the growth of seeds and emerging seedlings had been obtained. Theresults are set forth in the following table:

At the time of the observations, the check areas were found to support luxuriant and vigorously growing stands of wild oats.

Example III Fifty parts by weight of l,2,4,5tetrachlorobenzene, 47.4 parts of fullers earth, 1.3 parts of Nacconol NR and 1.3 parts of Daxad No. 27 were mechanically mixed and ground together to prepare a concentrate composition in the form of a wettable powder. A portion of this concentrate composition was dispersed in water to prepare an aqueous composition containing 2 pounds of the benzene compound per 100 gallons of ultimate mixture. Portions of this aqueous composition were employed for the treatment of soil for the control of the growth of the seeds and emerging seedlings of various plant species. In such operations the aqueous composition was sprayed upon the surface of soil areas in amounts suicient to supply 20 and 10 pound treatments of the tetrachlorobenzene compound per acre. Immediately prior to the applications, the soil areas had been prepared and seeded to the named plant species. Other areas similarly prepared and seeded were left untreated to serve as checks.

After three weeks, the treated areas were examined to ascertain what control of the growth of seeds and emerging seedlings had been obtained. The results are set forth in the following table.

At the time of observation, abundant stands of the named plant species were found in the check areas.

Example IV Finely ground 1,2,4,5tetrachlorobenzene was mechanically mixed with diammonium phosphate, (NH4)2HPO4, to produce a iinely divided solid composition containing l0 percent by weight of the benzene compound. This composition was employed for thetreatrnent of soil of good nutrient content for the control of wild oats. In such operations, the composition was applied to the surface of soil areas in amounts of 10 and 5 pounds of the tetrachlorobenzene compound per acre. Following the applications, the separate areas were raked to distribute the tetrachlorobenzene compound in 'the soil and the areas thereafter seeded to wild oats. Other areas were similarly prepared and seeded but left untreated to serve Vas checks.v "After vten days, Ythe treated areas were exfound to support abundant stands of wild oats.

Example V Finely ground 1,2,4,5tetrachlorobenzene was mechanically mixedv with a commercial fertilizer (10 percent each v of nitrogen, potassium oxide and phosphorus pentoxide) to prepare a composition containing about six percent by weight of the benzene compound. This composition was employed for the control of wild oats as described in Example IV. The treating and seeding operations were all :as previously described with the composition being distributed in an amount equivalent to 20 pounds of the benzene compound. Two weeks following these applications, the treated areas were examined and a 98 percent control of wild oats observed. At the time of the observations, the check areas were found to support abundant stands of wild oats.

Example VI Finely ground 1,2,4,5tetrachlorobe`nzene was mechanically mixed with attapulgite clay to prepare a composition containing 40 percent by weight of the benzene compound. This composition was employed for the control of wild oats as described in Example IV. ln the soil treating operations, the composition was employed in an amount sufficient to supply 10 pounds of the tetrachlorobenzene compound per acre. After ten days, the treated areas were examined and a 91 percent control of wild oats` observed. At the time of the observations, the check areas showed vigorously growing stands of Wild oats.

Example VII Portions of the wettable powder concentrate compositions containing 1,2,3,S-'tetrachlorobenzene and 1,2,3,4 tetraohlorobenzene as described in Example II were employed for the treatment of sandy loam soil of good nutrient content for tire control of the growth of the seeds Iand emerging seedlings of barley, peas, wild oats, J apanese millet and ax. `In such operations, the compositions were applied to the surface of soil areas in the amount of 10 pounds of tetrachlorobenzene compound per acre. Following the applications the top surface of the soil areas were thoroughly mixed and raked to distribute the tetrachlorobenzene compounds in the soil and the areas thereafter seeded to the named plant species. Other areas 'were similarly seeded but left untreated to serve as checks.

After three weeks, the treated areas were examined and the stands of barley, peas, wild oats, millet and ax were found to be substantially the same as in the case of the untreated checks.

What is claimed is:l

1. A Imethod which comprises applying to and mixing with soil infested by the seeds of wild oats, a growth inhibiting amount of 1,2,4,5tetrachloroben2ene.

2. An agronomical practice which comprises distributing in soil infested by the seeds of wild oats, a growth inhibiting amount of 1,2,4,5tetrachlorobenzene.

3. A method claimed in claim 2 wherein the benzene compound is distributed thru the soil in the amount of at least 8 parts by weight per million parts by weight of soil.

4. A method claimed in claim 2 wherein the soil is treated with a composition comprising l,2,4,5tetrachloro benzene fin intimate admixtulre with an inert herbicide adjuvant as a carrier therefor.

5. In the practice of agnicultural economy the method which comprises applying 1,2,4,'5tetrachlorobenzene to soil infested by the seeds of wild oats, the benzene compound -being substantially uniformly distributed to a depth of at least 0.5 inch andin the amount' of at least 1.7 pounds per acre inch of soil. l

References Cited in the file of this patent UNITED STATES PATENTS' Jones Dec.v 11,"1945 Stewart et al. Mar. 11, 1952 OTHER REFERENCES Frear: Catalogue of Insecticides and Fungicides,

1948, vol. I, p. 164; vol. II, p. 47.

King: .U.S. Dept. of Agriculture Handbook, No. 69, May 1954, p. 66.

Nex et al. in Weeds, vol. III, No, `3, July 1954, pp.

seydel .in Waterworks 'and sewerage," July 1938, 10 241-253.

pp. 688-690. Y f 

1. A METHOD WHICH COMPRISES APPLYING TO AND MIXING WITH SOIL INFESTED BY THE SEEDS OF WILD OATS, A GROWTH INHIBITING AMOUNT OF 1,2,4,5-TETRACHLOROBENZENE. 